diff --git a/CHANGELOG.md b/CHANGELOG.md
index cadb015..2999e4d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,10 @@
+# Version 18.3.1
+
+## Bugfixes
+
+* Fix `AttributeObserverTrait::mergeEntity()`: columns with a default value (`default-values`) were never emptied by `clean-up-empty-columns`, because the attribute code was looked up in the list of header positions
+* Fix XML DI configuration loading for `symfony/dependency-injection` 6.4 and 7.x: `ImportExtension` uses the loader shipped with Symfony again and falls back to the copied `XmlFileLoader` only where it is not available (Symfony 8)
+
 # Version 18.3.0
 
 ## Features
diff --git a/composer.json b/composer.json
index c1247dd..c5c9a70 100755
--- a/composer.json
+++ b/composer.json
@@ -12,6 +12,7 @@
         "league/event": "^2.2",
         "ramsey/uuid": "^4.2|^4.7",
         "symfony/mailer": "^5.4|^6.4|^7.4",
+        "symfony/dependency-injection": "^6.4|^7.0|^8.0",
         "laminas/laminas-filter": "^2.31",
         "techdivision/import-dbal": "^2.1",
         "techdivision/import-dbal-collection": "^2.2",
diff --git a/src/Observers/AttributeObserverTrait.php b/src/Observers/AttributeObserverTrait.php
index 4a147b6..e71eae1 100644
--- a/src/Observers/AttributeObserverTrait.php
+++ b/src/Observers/AttributeObserverTrait.php
@@ -465,9 +465,11 @@ protected function mergeEntity(array $entity, array $attr, $changeSetName = null
             // if the value is empty AND it is IN the array with default column values
             // BUT it is NOT in the array with columns we want to clean-up the default
             // column value has to be removed, because we do NOT want to override the
-            // value existing in the database
+            // value existing in the database. The clean-up column keys are the header
+            // positions of the columns, so the attribute code has to be translated first
             if (array_key_exists($this->attributeCode, $this->getDefaultColumnValues()) &&
-                array_key_exists($this->attributeCode, $this->getCleanUpEmptyColumnKeys()) === false
+                !($this->hasHeader($this->attributeCode) &&
+                    in_array($this->getHeader($this->attributeCode), $this->getCleanUpEmptyColumnKeys() ?? [], true))
             ) {
                 // remove the value from the array with the column values, because
                 // this is the default value from the database and it should NOT
diff --git a/symfony/DependencyInjection/ImportExtension.php b/symfony/DependencyInjection/ImportExtension.php
index 9dbb380..b8e1ce5 100644
--- a/symfony/DependencyInjection/ImportExtension.php
+++ b/symfony/DependencyInjection/ImportExtension.php
@@ -17,6 +17,7 @@
 use Symfony\Component\Config\FileLocator;
 use Symfony\Component\HttpKernel\DependencyInjection\Extension;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Loader\XmlFileLoader as SymfonyXmlFileLoader;
 use TechDivision\Import\DependencyInjection\Loader\XmlFileLoader;
 
 /**
@@ -39,7 +40,10 @@ class ImportExtension extends Extension
      */
     public function load(array $configs, ContainerBuilder $container): void
     {
-        $loader = new XmlFileLoader($container, new FileLocator(dirname(__DIR__) . '/Resources/config'));
+        // use the XML loader shipped with symfony/dependency-injection where available (6.4 and 7.x),
+        // symfony 8 removed it, so the copy of the 7.x loader has to be used there
+        $loaderClass = class_exists(SymfonyXmlFileLoader::class) ? SymfonyXmlFileLoader::class : XmlFileLoader::class;
+        $loader = new $loaderClass($container, new FileLocator(dirname(__DIR__) . '/Resources/config'));
         $loader->load('services.xml');
     }
 }